1. Field of the Invention
The present invention relates to a semiconductor memory card having a power supply card terminal for supplying electric power and a ground card terminal connected to the ground potential.
2. Background Art
In recent years, miniaturization and weight reduction of a mobile telephone and a personal computer which are provided with a nonvolatile memory chip have been advanced. Further, there is an increasing demand for a memory having a larger capacity and a product having a wide variety of functions.
Semiconductor memory cards such as an xD-Picture™ card are mainly used as storage media of a digital still camera. In the semiconductor chip configuration of the semiconductor memory card, a flash memory which is a nonvolatile memory used as a storage device and a controller chip which has a compatibility function to ensure compatibility with various devices are needed.
Further, in recent years, the capacity of the semiconductor memory card has been increased in accordance with the improvement in pixel resolution of the digital still camera and the extension of moving picture capturing time. The capacity of a semiconductor memory chip used as a storage medium is increased by reducing the size of memory cells. However, further miniaturization of the memory cell has become difficult, and further reduction in the chip size has also become difficult.
On the other hand, the package outer shape dimension of a semiconductor memory card is determined by a standard. When a chip having a size sufficiently smaller than the outer shape dimension of the semiconductor memory card is mounted, a sufficient space can be secured on a card board, so that a high degree of freedom of board wiring is obtained to facilitate the design of wiring. However, when a large capacity chip is mounted, the wiring space is reduced to cause the degree of freedom in the design of board wiring to be restricted.
In order to increase the capacity of a memory and provide a wide variety of functions for the memory, many semiconductor chips need to be mounted. However, with the advancement of miniaturization of products, the size of a circuit board mounted with the semiconductor chips is also reduced to thereby make it difficult to stack and mount many semiconductor chips.
Among conventional semiconductor memory cards, there is for example a memory card provided with: a semiconductor package which includes a base card having an opening part formed in the upper part thereof and a semiconductor memory for storing desired data, on the upper surface of which input/output card terminals electrically connected to the semiconductor memory and an external device to input/output signals, a power supply card terminal, and a ground card terminal are formed in a manner that the input/output card terminals, the power supply card terminal, and the ground card terminal are placed in the base card so as to be exposed via the opening part; and a label which is adhered to the upper part of the base card and covers the semiconductor package so as to allow at least a part of the input/output card terminals to be exposed (for example, see Japanese Patent Laid-Open No. 2003-346109).
Here, in the above described prior art, the input/output card terminals, the power supply card terminal, and the ground card terminal, each of which has a plate-like shape, are merely arranged side by side on the basis of a standard required for example, an xD-Picture™ card, regardless of the length of board wiring and the position of board terminals of the circuit board of the semiconductor package.
Therefore, for example, when the board terminals are arranged to be separated from the power supply card terminal or the ground card terminal, a problem may arise that the wiring length from the board terminals to a through-hole interconnection of the power supply card terminal or the ground card terminal becomes long to thereby hinder the improvement in responsiveness and the reduction in power consumption of the semiconductor memory card. Further, there is a problem that crosstalk between the board wiring may be generated due to the complication of board wiring structure and the like.